Patients' conscious recollections from cardiac anesthesia.

Objective: To estimate the current incidence of conscious recollections from the time of anesthesia, the contribution of anesthetic drugs to this incidence, and the patients' experience of cardiac anesthesia and surgery.

Design: Prospective, horizontal survey of cardiac surgery patients using structured interview method.

Setting: Tertiary care university hospital.

Participants: All cardiac surgery patients during 1 year (n = 1,218).

Interventions: None.

Measurements And Main Results: Of 1,218 patients operated on, 929 were interviewed. The patients' memories were classified to estimate the number of patients with possible or definite intraoperative awareness and later conscious recall. The use of anesthetics was estimated from anesthetic charts for patients with awareness and recall and control patients. These charts were compared using Poisson regression. The incidence of definite awareness with recall was 0.5% (5 patients), and the incidence of possible recall was 2.3% (21 patients). A lower dose of midazolam was used for the patients with awareness and recall. Only 1 patient rated the experience of awareness as the worst perioperative memory. Benzodiazepine premedication caused amnesia for the preoperative period but not for the time of anesthesia.

Conclusion: The incidence of awareness and recall is similar to the incidence reported during general surgery. Cardiac surgery does not carry increased risk of awareness. Benzodiazepines given during anesthesia are effective in decreasing the incidence of recalled awareness, and the experience of awareness is not often particularly traumatizing. Premedication with benzodiazepine is not effective in preventing recollection of anesthesia, however.